Making a new [[link]] that begins with a / (slash) is the common way to start a subpage. The page to which this link points is considered "subordinate" to its host page, and is titled and linked as [[Parentpage/Subpage]]. It is possible to create a subpage of a subpage (or a sub-subpage). At the top of each subpage or sub-subpage, you can find a backlink (aka breadcrumb) to the higher levels of the page.

Talk page archiving – both article Talk and User_talk pages are typically archived by moving discussion to numbered subpages. This allows the discussion to still be searchable, rather than requiring a hunt through the page history.

Temporary subpages in Talk namespace, usually formatted [[Talk:Example Article/Temp]] or [[Talk:Example Article/Dumping ground]], for example the kind of "/Temp" pages that can be created from Template:Copyvio. But avoid additional incoming and outward links that would make it appear as if this "/Temp" page is part of the encyclopedia: that is, in the case the Copyvio template is used, only this template, applied in article namespace, can link to the "/Temp" article from article or "main" namespace. See below Disallowed uses for further recommendations on how to avoid creating the impression a "/Temp" page is an encyclopedia page.

Writing drafts of major article revisions, e.g., [[Example Article/Temp]] in the main namespace, as you can get there accidentally using special:randompage — write these in the talk namespace, e.g. [[Talk:Example Article/Temp]]. Also, avoid incoming and outward links regarding such "Talk:.../Temp" page that might create the impression this is an encyclopedia page before it is, e.g.:

surround "category" links by "nowiki" tags, so that the temp page doesn't show up in a non-project category as if it were an article, example: <nowiki>[[Category:Incredibly smart people]]</nowiki>. The "nowiki" tags should be removed only when the "temp" content is moved to its place in article namespace. (This is an outward link example.) Another solution: put a colon before word "Category", for example, write [[:Category:Shamanism]] instead of [[Category:Shamanism]]. In this case, it will be still linkable, but it will not make the subpage appear on category pages.

don't create navigational templates that make it appear as if this temp page is part of a series of encyclopedia articles, for example, don't do this: "... | [[John I of Doeland]] | [[Talk:John II of Doeland/Temp|John II of Doeland]] | [[John III of Doeland]] | ...". (this is an incoming link example).

Draft pages mistakenly created in the main namespace should be moved as appropriate, or deleted if they are inactive and redundant to the main article.

Using subpages for permanent content that is meant to be part of the encyclopedia.

The MediaWiki software supports selectively allowing or disallowing the creation of subpages in various namespaces. In namespaces where subpages are supported, you can create a subpage simply by linking to the name of the subpage, prefixed with a slash (e.g. [[/Archive]]). For Wikipedia, the User, Talk, and Wikipedia namespaces have subpages turned on; the main (article) namespace does not have this feature turned on, as strictly hierarchical organisation of articles is discouraged, and other distinctions are better made by placing pages in other namespaces (e.g. discussions go in "Talk:", and templates in "Template:").

Some topics have a slash in the name — e.g.GNU/Linux naming controversy or OS/2. This is not a problem. If that's what the thing is called, use the slash. In article namespace this doesn't define a subpage.

Subpages were originally used on Wikipedia to differentiate between subjects to create topical hierarchies of articles, but this proved unworkable because articles tend to belong in more than one hierarchy. The present system of disambiguation was adopted instead, and the Wikipedia:Do not use subpages policy had to be rigorously enforced, as well as retroactively applied. As of mid-2004, the category system supports hierarchical organization while still allowing an article to belong to multiple categories.